Sewing machine lubrication



Dec. 18, 1962 s. J. KETTERER ErrAL 3,068,

SEWING MACHINE LUBRICATION 2 Shoots-Shut 1 INVENTORS'. Stanley J. Ke/terer m BY Darwin 6. Smith. 22 XITTORNEY Filed June 24, 1959 1962 5. J. KETTERER EI'AL 3,068,820

SEWING MACHINE LUBRICATION Filed June 24, 1959 2 Sheets-$11061 2 INVENTORS. Stanley J. Kai/ere! and BY Darn 1h 6. Smith.

ATTORNEY United States Patent 3,068,820 SEWING MACHINE LUBRICATION Stanley J. Ketterer, Stratford, and Darwin G. Smith, Bridgeport, Conn., assignors to The Singer Manufacturing Company, Elizabeth, N.J., a corporation of New Jersey Filed June 24, 1959, Ser. No. 822,575 1 Claim. (Cl. 112-256) The lubrication requirements for a high speed sewing machine parts and devices and, more particularly, to a novel lubricating device adapted for use with high speed sewing machines.

The lubrication requirements for a high speed sewing machine are extremely critical. Not only must the minimum requirements be met under all conditions, so as to prevent overheating, wear, and the like, but an excess of lubrication must be avoided to prevent spoilage of the work fabrics being stitched.

It is an object of this invention to provide a.- simple and effective lubricating system which supplies the critical needs of a high speed sewing machine.

Another object of this invention is to provide an efficient lubricant transporting mechanism in which heating of the lubricant and consequently of the sewing machine casing, because of inefficient turbulance, is minimized.

Still another object of this invention is to provide a novel pump means for a sewing machine lubricating system driven in response to the operation of the stitch forming instrumentalities of the sewing machine such that delivery of lubricant will cease immediately when sewing is stopped on th machine.

With the above and other objects and advantages in view as will hereinafter appear, this invention comprises the devices, combinations and arrangements of parts hereinafter described and illustrated in the accompanying drawings of a. preferred embodiment in which:

FIG. 1 represents a vertical cross-sectional view of a rotary hook for a sewing machine together with the adjoining parts and devices and having the lubricating system of this invention applied thereto,

FIG. 2 represents a vertical cross-sectional view taken substantially along line 2-2 of FIG. 1, and

FIG. 3 represents a horizontal cross-sectional view of the mechanism illustrated in FIG. 1.

Illustrated in FIGS. 1 and 3 is a conventional rotary hook 11 for a lock stitch sewing machine. As is well known in the art, the rotary hook is adapted to be driven two revolutions for each endwise reciprocation of a needle (not shown) so as to carry a needle thread loop completely about a bobbin case base 12 which is journaled in a raceway 13 formed in th rotary hook. The bobbin case base accommodates a bobbin (not shown) on which is wound a bobbin thread that is concatenated with the needle thread by the rotary hook to form lock stitches, it being understood that the bobbin case base 12 is prevented from rotating with the rotary hook.

In the preferred embodiment of the drawings, the lubricating system of this invention is illustrated as applied to the problem of supplying lubricant to the raceway 13 of the rotary hook. The rotary hook 11 is perferably formed with a cylindrical shank 14 slabbed to define a tongue 15 seated in a transverse groove 16 formed in the extremity of a hook driving shaft 17. The shaft 17 is journaled in a bushing 18 fixed in a web 19 of the sewing machine casing.

The rotary hook shank 14 and the hook driving shaft 17 are each secured in a connecting collar 21 by set screws 22 with the tongue 15 seated in the transverse groove 16. The connecting collar is formed with an eccentric 23 embraced by a forked pitman 24 fulcrumed on a stud 25 secured in the sewing machine casing web 19. The

3,068,820 Patented Dec. 18, 1962 ice pitman 24 carries a rotation restraining member (not shown) for the bobbin case base 12 which not only prevents rotation of the bobbin case, but which also oscillates to open a gap between the rotation restraining member and the bobbin case base for the free passage ofthe needle thread loop therebetween.

A lubricant reservoir 30 is provided in the machine casing beneath the hook driving shaft 17. A top cover 31 on the reservoir is formed with an opening 32 through which depends an endless flexible conveyor preferably in the form of an ordinary bead-chain'33 of the conventional ty-pe comprising alternate hollow spherical members 34, interconnected by cylindrical pins 35 which are upset within the hollow spherical members to link the parts together.

The bead-chain encircles and rests upon the shaft 17 and is constrained thereon by an upwardly open chain accommodating groove 36 formed in the shaft bushing 18, and by an arched cover member 37 which spans the groove 36 and is secured to the bushing 18 by the set screw 38 so as to prevent the bead-chain from accidentally shifting out of the groove 36. i

In FIG. 2, the arrow indicates the direction of rotation of the hook driving shaft 17. The slot 36'in the bushing 18 on the side toward which the hook driving shaft moves during rotation thereof, is formed with a surface 39 flared outwardly from the cylindrical shaft engaging bearing surface of the bushing. The flared surface 39, together with the hook driving shaft 17, defines a wedge-shaped catch-basin for lubricant on the external surface of the hook driving shaft.

The hook driving shaft is formed adjoining the groove 36 with a spiral groove 50leading to a radial port 51 which communicates with an axial'bore 52 formed in the hook driving shaft. The'spiral groove 50 also leads to an annular hook shaft portion 53 of reduced diameter which is joined by a passageway 54 in the bushing 18, a passageway 55 in the web 19, and a radial port 56 formed in the fulcrum stud 25 to an axial bore 57 in the fulcrum stud. The fulcrum stud axial bore 57 extends to the free extremity of the fulcrum stud which overhangs the lubricant reservoir and in which free extermity a spring clip 58 is disposed in order to direct lubricant therefrom directly back into the reservoir without driveling. A needle valve stem 59 threaded into the fulcrum stud 25 serves to constrict the opening of the radial port 56 into the axial fulcrum stud bore 57. The passageways 54 and 55, the radial port 56, and the stud bore 57 thus provide a bypass adjustable by the valve stem 59' to control the amount of lubricant delivered by the spiral groove 50 into the axial hook shaft bore 52.

The cylindrical shank 14 of the rotary hook is formed with a threaded bore 60 in which is accommodated an insert 61 formed with a small bore 62 opening into a larger cylindrical bore 63 within which is disposed a metering pin 64 the function of which is to provide a slight restriction to the passage of lubricant in order to provide for pressure to be developed in the bore 52 of the hook driving shaft in order that the bypass 5457 might operate effectively.

The rotary hook 11 is formed with a radial bore 70 leading from the threaded bore 60 to a recess 71 formed near the periphery of the hook. A radial port 72 joins the recess 71 with the hook raceway 13. Circular discs 73 and 74 are seated tightly in access apertures in the rotary hook leading to the recess 71 and the threaded bore 60.

Lubricant delivered along the axial bore 52 of the hook driving shaft is prevented from escaping between the shank 14 of the rotary hook and the connecting member 21 by means of a packing ring 75 set into the connecting member. Lubricant which may escape between the hook driving shaft 17 and the connecting member 21 will be collected by the oil sling flange 76 on the connecting member and thrown off into a recess 77 formed in the web 19 for drainage down the inclined passageway 78 back into the lubricant reservoir. Any lubricant which makes its way along the'hook driving shaft' 17 beyond the oil sling flange 76 will be pumped by the spiral groove 79 in the hook shaft back into the annular reduced portion 53.

The complete lubricating system illustrated in the drawings may b considered as a two-stage pump. The first stage involves the raising of lubricant by means of the bead-chain from the reservoir to the exterior surface of the hook driving shaft. The second stage involves the forcing of lubricant by the spiral groove 50 into the axial bore of the hook and thence to the hook raceway.

The bead-chain expedient iby which the lubricant is raised from the reservoir 30 to the hook drive shaft affords many distinct advantages. The construction is exceedingly simple and economical of manufacture, the only moving part, other than the hook shaft, is the beadchain, and, therefore, servicing and wear of parts is minimized. The drive of the bead-chain by the hook driving shaft is such as to provide readily for slippage, and, therefore, one in which the power delivered to the bead-chain by the shaft is limited. During periods of rapid acceleration of the hook drive shaft, therefore, the drag imposed by the bead-chain is circumvented by slippage of the chain on the shaft. Similarly, during the periods of high speed operation of the sewing machine, slippage of the bead-chain will prevent unnecessarily large power drain from the hook shaft to the bead-chain, therefore, averting unnecessary beating of the lubricant in the reservoir into a froth as in commonly experienced with positively coupled lubricant pumping devices in the prior art what is claimed herein is:

In: a sewing machine having a rotary hook formed with a raceway adapted to accommodate a stationary bobbin case, a hook driving shaft connected with said l-Iaving thus described the nature of the invention,

rotary hook and formed with an axial bore, lubricant conducting passageways extending from said hook shaft bore to said rotary hook raceway, a bushing formed with a cylindrical bearing surface snugly embracing said hook driving shaft, spiral groove pump means arranged between said hook driving shaft and said bushing for forcing lubricant from the external surface of said hook driving shaft into the axial bore thereof for delivery to the hookraceway, means for delivering lubricant to the external surface of said hook driving shaft comprising a lubricant reservoir carried in said sewing machine beneath the hook driving shaft, said bushing formed with an upwardly open conveyor accommodating slot exposing said hook driving shaft, an endless conveyor encircling said hook driving shaft comprising a bead'chain including alternate hollow spherical beads and cylindrical connecting pins snugly accommodated in apertures in the beads and having enlarged head portions formed within the hollow beads tolock the bead-chain parts together, said endless conveyor disposed in said upwardly extending conveyor slot and depending into said lubricant reservoir, said conveyor accommodating slot in the hook drive shaft bushing being formed on that side toward which the external surface of th hook shaft movesduring rotation of said hook shaft with a surface portion flaring gradually'outwardly from the cylindrical shaft engaging bearing surface of the bushing, said flaring bearing surface-portion together with the external surface of the hook driving shaft defining a wedge shaped catch basin for admission of lubricant from the external surface of the hook driving shaft to the spiral groove pump means.

References Cited in the file of this patent UNITED STATES PATENTS Zonis Dec, 23, 1941 UNITED STATES PATENT OFFICE CERTIFICATE OF QRECTION Patent No, 3,068,820 December 18 Stanley J Ketterer ei; ale

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 10, for "The lubrication requirements for hlgh speed read This invention. relates to the luhricatien 0i Signed and sealed this 2nd day 0f July 1963a (SEAL) Attesi:

ERNEST w. SWIDER DAVID LADD Attesiing Officer Commissioner of Patents 

